How to run Capistrano task locally from remote server?

Question

Use case:
Suppose I have a Capistrano task defined, for example cap resque:start.
It takes :set values such as amount of workers from my deploy.rb.
Suppose I want to start resque workers on server reboot.
I can copypaste them to some post-reboot script, but if I change :set amount of workers or other configs, I'll need to change post-reboot script as well.

Instead of that, we can execute cap locally:resque:start in our post-reboot script, which will automatically take current amount of workers we set in deploy.rb.

Answer 1

1. in Gemfile, add all Capistrano gems from :development to :production

2. create a task cap locally:resque:start:

   namespace :locally do
     namespace :resque do
       task :start do
         run_locally { Rake::Task["resque:start"].execute }
       end
     end
   end
   

3. add remote host to your authorized_keys on remote host (because Capistrano 3 requires stage set even if we are executing task locally. luckily ssh connection to localhost will be fast):

   1. ssh-keygen -t rsa
   2. cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
   3. chmod og-wx ~/.ssh/authorized_keys

4. and now, on your remote production server, cap production locally:resque:start.